1. Field of the Invention
The present invention relates to recovery of crude oil from oil-bearing subterranean formations through use of micellar systems.
2. Description of the Prior Art
Much patented and non-patented literature has been published regarding the formulation of micellar systems for the optimum recovery of petroleum from subterranean formations. Also, the measurement of zeta potential has been covered in a number of publications, primarily in the biological and biophysical fields. The following U.S. Patents discuss zeta potential to some extent: U.S. Pat. No. 3,454,487 teaches measurement of the electrokinetic potential (zeta potential) in an electrophoresis cell; U.S. Pat. No. 3,542,674 teaches the measurement of zeta potential to determine the optimum conditions for flocculation; U.S. Pat. No. 3,580,871 teaches techniques for preparation of polymer dispersions with positive zeta potential; U.S. Pat. No. 3,620,828 teaches the neutralization of zeta potential of clay pigments with polyethylene amine and a 3,5-piperidium homopolymer to provide conductive coatings on paper used in direct electrophotographic copiers; German Offen. No. 2,249,161 teaches the determination of optimum conditions for industrial water and waste treatment by determination of the zeta potential; and U.S. Pat. No. 3,639,327 teaches the use of cationic agents to lower the zeta potential in preparing latex adhesive. The following literature also deals with zeta potential, surface adsorption and surface potential, but does not relate to oil recovery: "Adsorption from Aqueous Solution," (ed. R. F. Gould), American Chem. Soc. Publication No. 79 (1968); R. J. Alkinson et al., J. Phys. Chem. 71, 550 (1967); D. W. Fuerstenau, Chemistry of Biosurfactants, Vol. 1, (M. L. Hair, ed.), Marcel Dekker, N.Y. (1971); D. W. Fuerstenau and H. J. Modi, J. Elec. Chem. Soc., Vol. 106, 336 (1959); J. J. Kipling, "Adsorption from Solution of Non-Electrolytes," Academic Press (1965); R. H. Ottewill and J. N. Shaw, Disc. Fara. Soc. No. 42, 154 (1966); J. Overbeek, J. Colloid Sci. (H. R. Kruyt, ed.), Vol. 1, Elsevier (1952) Chap. 4 and 5; G. A. Parks, Chem. Rev. 65, 177 (1965); G. A. Parks and P. L. de Bruyn, J. Phys. Chem. 66, 967 (1962); G. Schay, Chapter 3 "Surface and Colloid Science V. 2," Wiley-Interscience (1969); and F. Tokiwa, J. Coll. Int. Sci. 28, 145 (1968).
The present invention embodies the discovery that zeta potential offers a numerical measurement of a parameter which permits the optimizing of oil-recovery and the minimizing of undesirable adsorption of surfactant on rock formations.